Strabismus and the whole body
Developmental optometrists have always treated strabismus as a manifestation of a whole-body problem. They have found that often improvements in gross motor an fine motor skills that are part of a vision therapy program contribute to improvements in a patient's ability to control their strabismus.
Vision therapy is based on the concept of neuroplacitity. Neuroplacticity refers to the ability of the brain to reorganize itself though a program of rehabilitative therapy and fix problems that arise from the failure of the brain and eyes to communicate properly.Strabismus is one such problem. The eye turns in strabismus patients are usually not caused by problems with the muscle itself. The problem is in the eye-brain connection that controls eye movement.
A holistic approach to treating strabismus is validated by research studies. For example, an important study appeared in the May 2014 issue of the journal Vision Research which investigated how the information from eye-muscles muscles affects postural stability in adults with binocular vision disorders and demonstrated that those with binocular vision disorders showed significantly worse balance control than those without binocular vision disorder, even when they were only using only one eye.
The study showed that inaccurate signals related to the eye muscles have an impact body balance and that this effect can last into adulthood even where subjects had surgery as children to make the eyes appear straight.
The study also shows that specific therapeutic tasks (i.e. vision therapy) can allow patients with strabismus to develop better body balance.
The study adds to the growing body of research that suggests that strabismus is a whole-body problem that results in impairments, adaptations and compensations on many levels throughout the body, which often last into adulthood.
Why is this research exciting? It counteracts the notion that strabismus is an isolated eye muscle problem that has little bearing other than cosmesis. The appearance of the eyes is only one feature of strabismus, better appreciated as a difficulty in multimodal coordination. This presents new opportunities to conceive of the synergy between extra-ocular muscle (EOM) surgery and optometric vision therapy, somewhat analogous to the synergy between orthopedic surgery and physical therapy.
When conceived in this fashion, the cognitive and attentional resources employed in optometric vision therapy help the brain to coordinate both eyes through activities mediated through the cerebellum. Even when [eye muscle] surgery or optometric vision therapy do not achieve bi-foveal alignment or random dot stereopsis, very meaningful gains can be realized in improved head to toe motor control.
The role of vision therapy features prominently in this study. Here is what the authors say:
These findings emphasize the role of the eye-muscle signals in postural control and suggest that suitable vision therapy can be the appropriate way to improve body balance/motor functions in people with binocular vision disorders.
In short, the authors documented that patients with esotropia [a type of strabismus where the eye turns in towards the nose] have shorter step widths during gait, consistent with constricted binocular visual fields as reported in the literature. They noted previous reports that strabismus surgery for esotropia can result in a wider binocular visual field. Optometric authors such as Chisholm in the UK have recognized that the Esterman Binocular Visual Field Plot is more indicative of dynamic performance in activities such as driving, and undoubtedly this is a standardized clinical measure that will become more useful not only in the management of glaucoma but in strabismus as well. Conversely, the authors in this study report that patients with exotropia [a type of strabismus where the eyes turn out towards the wall] have wider step widths during gait, consistent with expanded binocular visual fields.
The authors conclude their paper by noting that their results about walking strategies of patients with congenital or early onset esotropia or exotropia suggest the application of integrated rehabilitation therapies focused not only on gait training, but also on visual field training. Although the authors appear to be oblivious that optometric vision therapy has incorporated these strategies...
Impaired Body Balance Control in Adults With Strabismus Vision Res 2014 May 01;98(-)35-45, A Przekoracka-Krawczyk, P Nawrot, M Czaińska, KP Michalak
Frontiers in Human Neuroscience
Aprile I, Ferrarin M, Padua L, Di_sipio E, Simbolotti C, Petroni S,
Tredici C and Dickmann A(2014) Walking strategies in subjects
with congenital or early onset strabismus. Front. Hum. Neurosci.
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